Numerical assessment of steam nucleation on thermodynamic performance of steam ejectors

Steam nucleation is a prevalent phenomenon in supersonic steam flows. It seems to occur to the high-speed flow in steam ejectors. The fundamental approach in evaluating the performance parameters of ejectors is to consider steam as an ideal gas. However, in a supersonic flow of vapor under specific circumstances, nucleation phenomenon occurs and consequently vapor condensation is observed. Therefore, it is necessary to consider the effects of moisture content on the performance of such devices. In the present study, the numerical simulation of a steam ejector under the assumption of homogenous nucleation is undertaken. The novelty of this research is the analytical modeling of the effects of wet steam on the aerodynamics and thermodynamic performance of steam ejectors. The numerical results are validated in a Laval nozzle with a set of experimental data reported in the literature. The performance parameters emerge numerically from the analysis, and information concerning the deviation of wet steam flow properties from the dry steam is revealed. It is shown that steam condensation in supersonic regions reduces the maximum value of flow Mach number in the ejector and increases the ejector’s performance parameters in comparison to those of assuming steam as a dry gas.

► A novel study of wet-flow in an ejector is undertaken.
► Numerical prediction of internal phenomena with droplet generation in a supersonic stream.
► There is an extended shock wave position in the ejector throat in the case of wet steam flow.
► Substantial increasing in Entrainment Ratio and Compression Ratio is observed in the case of a wet steam simulation.